Do mirrors reflect reality in agonistic encounters? A test of mutual cooperation in displays

Robert W. Elwood*, Velizara Stoilova, Amy McDonnell, Ryan L. Earley, Gareth Arnott

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

34 Citations (Scopus)


Animals frequently engage in mutual displays that may allow or at least help decisions about the outcome of agonistic encounters with mutual benefit to the opponents. In fish these often involve lateral displays, with previous studies finding evidence of population-level lateralization with a marked preference for showing the right side and using the right eye. Because both opponents tend to show this preference a head to tail configuration is formed and is used extensively during the display phase. Here we tested the significance of these lateral displays by comparing displays to a mirror with those to a real opponent behind a transparent barrier. The frequency of displays was lower to a mirror but the individual displays were of greater duration indicating a slower pace of the interaction with a mirror. This suggests that fish respond to initiatives of real opponents but as mirror images do not initiate moves the focal fish only moves when it is ready to change position. However, lateralization was still found with mirrors, indicating that the right-side bias is a feature of the individual and not of the interaction between opponents. We discuss implications for ideas about the evolution of mutual cooperation and information exchange in contests, as well as the utility of the use of mirrors in the study of aggression in fish.

Original languageEnglish
Pages (from-to)63-67
Number of pages5
JournalAnimal Behaviour
Early online date26 Sep 2014
Publication statusPublished - Nov 2014


  • Contest behaviour
  • Information exchange
  • Lateral displays
  • Lateralization
  • Mirror test

ASJC Scopus subject areas

  • Animal Science and Zoology
  • Ecology, Evolution, Behavior and Systematics


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